package netWork;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;

public class UdpEchoSever {
    private DatagramSocket socket=null;


    public UdpEchoSever(int port) throws SocketException {
        socket=new DatagramSocket( port);
    }
    //通过start启动服务器的核心流程
    public void start() throws IOException {
        System.out.println("服务器启动！");
        while (true){
            //此处死循环不停的处理客户端的请求

            //1.读取客户端的请求并分析
            DatagramPacket requestPacket=new DatagramPacket(new byte[4096],4096);
            socket.receive(requestPacket);
            //上述需要转化为二进制，需要转换为字符串
            String request=new String(requestPacket.getData(),0,requestPacket.getLength());

            //2.根据请求计算响应，就是回应服务器，就是请求
            String response=process(request);


            //3.返回客户端
            DatagramPacket responsePacket=new DatagramPacket(response.getBytes(),response.getBytes().length,requestPacket.getSocketAddress());
            socket.send(responsePacket);

            //4.打印日志
            System.out.printf("[%s:%d:] req=%s,resp=%s\n",requestPacket.getAddress(),requestPacket.getPort(),request,response);
        }
    }
    private String process(String request){
        return request;
    }

    public static void main(String[] args) throws IOException {
        UdpEchoSever sever=new UdpEchoSever(9090);
        sever.start();
    }
}
